Testing the relative importance of local resources and landscape connectivity on Bombus impatiens (Hymenoptera, Apidae) colonies

Abstract

Bee populations are decreasing worldwide. The underlying causes are likely determined by factors at different scales. We tested the relative importance of local resources and landscape connectivity on 64 bumblebee (Bombus impatiens) colonies in experimentally isolated and connected habitat fragments. We used colony mass, no. of workers, and no. of gynes to estimate colony performance. Landscape connectivity did not significantly affect colony performance, but local floral resources had a significantly positive effect, especially in isolated fragments. These results suggest that bumblebee colonies encountered sufficient floral resources within the local 1.4 ha habitat fragments to support colony growth, making long-distance foraging trips to neighboring fragments unnecessary. From a conservation perspective, we suggest that efforts to improve colony performance should prioritize boosting local floral resources over manipulation of large-scale landscape features.